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Protein Nitration Influences Allergic Reactions
Food proteins are nitrated through various processes. Just how these
processes affect food allergies, however, is only now coming to light.
The latest findings of a research project funded by the Austrian Science
Fund FWF are being presented today at an international symposium in Italy.
The findings show that in the case of a particular food protein the nitrated
form can trigger a stronger allergic reaction than the non-nitrated form.
At the same time, however, this nitrated form of the protein is better
digested and therefore rendered "harmless".
It has been know for some time now that many proteins cause allergies.
The fact that proteins can be altered - nitrated - by environmental influences
and that their allergenicity can increase as a result is also known, but
is a more recent discovery. What was not at all known up to now was whether
the nitration of food proteins through environmental pollution or inflammatory
processes in the body influences allergies. As of this past weekend, we
know substantially more: At the 28th Symposium of the Collegium Internationale
Allergologicum on Ischia, Italy, Dr. Eva Untersmayr presented the initial
findings of an ongoing research project funded by the Austrian Science
Fund FWF.
Clear Yet Contradictory Results
Dr. Untersmayr, who works at the Department of Pathophysiology at the
Medical University of Vienna, explains her very surprising findings: "Increased
allergenicity and yet fewer allergic reactions. This is - to pinpoint
it - the result of our studies on ovalbumin, an important allergen found
in eggs. If you compare the concentration of allergy markers, the IgE
antibodies, following the injection of ovalbumin in nitrated and non-nitrated
form in our animal model, a clear picture emerges: the nitrated ovalbumin
has a stronger allergenic effect. A clear picture also emerges when both
forms of the protein are administered in food and the same markers are
measured again: the nitrated ovalbumin causes fewer allergic reactions.
The two outcomes thereby appear contradictory - at first glance."
For Dr. Untersmayr and her colleague Dr. Susanne Diesner this result
was an important indicator of the fact that although the nitrated form
of the protein had a stronger inflammatory effect than the non-nitrated
form, the nitrated protein is degraded faster in the digestive tract.
To substantiate their ideas, they analysed the time taken for the enzymatic
digestion of the two forms of protein in a model system that simulated
gastric conditions. They actually succeeded to demonstrate that the nitrated
form is rapidly digested, while the non-nitrated protein remained stable
for up to two hours. "A food protein can actually only trigger an
allergic reaction if it survives exposure to the gastric juices unharmed
and is absorbed into the blood in the intestine. This is not the case
with the nitrated ovalbumin we used as a model allergen - despite the
fact that it is actually more allergenic," explains Dr. Untersmayr.
What Next?
The data presented in Italy this weekend also show that the effect of
the nitration is already a complex process in animal models. Therefore,
it would not be possible to apply the findings to the human organism without
further studies. And this is precisely what Dr. Untersmayr would like
to do next as part of her FWF project. Together with her research partners,
the group of Professor Albert Duschl in Salzburg, she is also interested
in the interaction between the bacterium Heliobacter pylori, one of the
causes of gastric inflammation, and the nitration of food proteins. In
these studies, Dr. Untersmayr is concentrating on the enzyme urease, which
is produced by H. pylori. Should it emerge that food proteins are nitrated
by urease - and that these proteins are more allergenic than the non-nitrated
form - this would have to be taken into account in future treatment concepts
for both allergy sufferers and patients with inflammation of the stomach.
For Dr. Untersmayr this would mean that the value of a basic research
project would not only be reflected in terms of the knowledge gained,
but also in concrete benefits for patients.
Scientific Contact
Dr. Eva Untersmayr
Medical University of Vienna
Institut für Pathophysiologie
Währinger Gürtel 18-20 / E4Q
1090 Wien, Austria
T +43 / 1 / 40400 - 5121
M +43 / 650 / 778 75 58
E eva.untersmayr@meduniwien.ac.at
Austrian Science Fund FWF
Mag. Stefan Bernhardt
Copy Editing & Distribution
PR&D - Public Relations for Research & Education
Campus Vienna Biocenter 2
1030 Wien, Austria
T +43 / 1 / 505 70 44
E contact@prd.at
W http://www.prd.at
Vienna, 26.04.2010
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